1. Field of the Invention
The present invention relates to a molding-condition setting method for an injection molding machine, which method is suitable for use in the case where molding conditions are set by means of CAE (computer aided engineering).
2. Description of the Relevant Art
In general, setting of molding conditions in an injection molding machine requires a large number of trial molding operations and a long setting time, because the setting work greatly depends on the know-how and experience of an operator, and various physical values affect one another. Therefore, conventionally, virtual molding (simulation) has been performed by use of CAE for injection molding, and molding conditions have been set on the basis of the virtual molding, as disclosed in, for example, Japanese Patent Application Laid-Open (kokai) No. 8(1996)-230006.
In virtual molding by use of CAE, phenomena occurring within a mold within a short period of time; i.e., the result of simulation on resin temperature, pressure, shear rate, etc. can be reflected in molded products. Therefore, if phenomena occurring within a mold can be grasped accurately, use of CAE enables optimization of molding conditions and stable molding of non-defective products. As described above, since CAE can calculate all phenomena occurring within a mold, if analysis accuracy is high, CAE serves as an assisting apparatus suitable for optimization of molding conditions.
However, when a conventional CAE system is used in actual molding, many problems arise. For example, in virtual molding by use of CAE, the results of simulation on phenomena which occur within a mold within a short period of time can be reflected in molded products. However, since molding conditions during actual molding do not coincide with the molding conditions determined by CAE, a large analysis error is produced. In practice, the results of actual molding greatly differ from the results of virtual molding. Therefore, the conventional molding-condition setting method utilizing CAE cannot set optimal molding conditions efficiently and with ease and cannot utilize CAE sufficiently.
An object of the present invention is to provide a molding-condition setting method for an injection molding machine which can solve the problem that the results of actual molding greatly differ from the results of virtual molding, and eliminate analytical errors to thereby enable efficient, easy setting of optimal molding conditions.
Another object of the present invention is to provide a molding-condition setting method for an injection molding machine which attains the most preferable results in setting accuracy, setting efficiency, etc.
In order to achieve the object as described above, the present invention provides a method for setting molding conditions of an injection molding machine through performance of virtual molding by CAE, the method comprising the steps of: setting provisional molding conditions for the injection molding machine and performing actual molding; obtaining an actual profile showing variation in load pressure actually measured during at least an injection step of the actual molding; performing virtual molding by means of the CAE while using the provisional molding conditions; obtaining a virtual profile showing variation in load pressure simulated during at least an injection step of the virtual molding; changing the provisional molding conditions by means of the CAE in such a manner that the virtual profile coincides with the actual profile, to thereby obtain intermediate molding conditions; and optimizing the intermediate molding conditions so as to obtain molding conditions for the injection molding machine.
Preferably, a flow-front position in the virtual molding performed by use of the CAE is determined, a gate position is obtained from the actual profile, and load pressure after the gate position is used.